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Discussion Starter #1
So I've been looking for crappy old cars with hopefully good bones to serve as my first car EV (I have built e-bikes and 90% of an EV motorbike).

I found an old 70s Opel GT for ~$1500. It doesn't seem too rusted, looks like someone's already sanded the rust off, apparently it runs (doesn't matter to me much). Seats are chewed up.

I like building things cheap, I'm not looking for performance, I want something to build without breaking the bank or feeling guilty about wrecking a classic, so, it seems a good fit that way.

It weighs about 2000lbs. It's 13.5' long. 2 seater. Described as "half a Corvette" (half the weight, half the power if you're lucky). Doesn't have a hatchback or a trunk, just a weirdly large parcel shelf. Front engine RWD.

I don't know enough about cars to know what to walk away from.

I already have a motor, a ~350lb 3ph motor from a forklift. I have a source of batteries.

Any reason I wouldn't want an Opel GT as my donor? Any gotchas that I'm not knowledgeable enough to know to ask about? Anything critical I should pay attention to when I'm inspecting the car?
 

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So I've been looking for crappy old cars with hopefully good bones to serve as my first car EV (I have built e-bikes and 90% of an EV motorbike).



I found an old 70s Opel GT for ~$1500. It doesn't seem too rusted, looks like someone's already sanded the rust off, apparently it runs (doesn't matter to me much). Seats are chewed up.



I like building things cheap, I'm not looking for performance, I want something to build without breaking the bank or feeling guilty about wrecking a classic, so, it seems a good fit that way.



It weighs about 2000lbs. It's 13.5' long. 2 seater. Described as "half a Corvette" (half the weight, half the power if you're lucky). Doesn't have a hatchback or a trunk, just a weirdly large parcel shelf. Front engine RWD.



I don't know enough about cars to know what to walk away from.



I already have a motor, a ~350lb 3ph motor from a forklift. I have a source of batteries.



Any reason I wouldn't want an Opel GT as my donor? Any gotchas that I'm not knowledgeable enough to know to ask about? Anything critical I should pay attention to when I'm inspecting the car?
Can you provide some pictures? Rust is a deal breaker a lot of the time, and it can be super hard to tell.

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Discussion Starter #3
Can you provide some pictures? Rust is a deal breaker a lot of the time, and it can be super hard to tell.
I meant, suitable as a donor in theory, not, this particular car.

But, yes, I'm going to go take some pictures when I go look at it, I'll be sure to post them.

Obviously rust is bad, but why?

The outside doesn't look like there's rust holes or anything. He does say the floor is rusted through in parts.

To my very amateur guessing, outsides of the car being rusty is scary, because that's cosmetic. Floor being rusty is not scary, because I can just patch it by welding some sheet metal on. I can weld, I've never welded on a car, I don't know if my guess is true.

What's especially important to look at when I go to see it, rust-wise, or, anything else-wise. I'm very much not a car-guy so I don't have any car-guy instincts.
 

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I meant, suitable as a donor in theory, not, this particular car.

But, yes, I'm going to go take some pictures when I go look at it, I'll be sure to post them.

Obviously rust is bad, but why?

The outside doesn't look like there's rust holes or anything. He does say the floor is rusted through in parts.

To my very amateur guessing, outsides of the car being rusty is scary, because that's cosmetic. Floor being rusty is not scary, because I can just patch it by welding some sheet metal on. I can weld, I've never welded on a car, I don't know if my guess is true.

What's especially important to look at when I go to see it, rust-wise, or, anything else-wise. I'm very much not a car-guy so I don't have any car-guy instincts.
Rusty floor pans can be telling. Where did the water come from? Is the windshield seal bad? Is the cowl rusted through and it's draining inside the car? Was it driven on salty roads in the winter, rusting from the bottom, and there's further damage? What do the inside of the doors look like (behind the door cards)? Wheel wells (inner and outer)? Trunk floor? Frame rails? Pinch welds on the body? It's normal to find nasty rust in many of those places that would render an otherwise fun project a bottomless money pit.

Whatever rust you see is usually the tip of the iceberg.

Additionally, an Opel GT is a unibody car. The floor pans are structural, so it's essential that repairs be properly made. Welding floor pans is not a big deal, necessarily, but anything else on the car can be. It's very easy to warp. Not trying to lecture, as I'm sure you already know, but that's another point against anything that's rusty.

Check for bondo - bring a magnet. There may be gaping rust holes covered with bondo and then painted. A magnet will help you find that.

There are enough cool cars out there - if the rust is anything more than just on the surface (minimal pitting), I'd just walk away. No bubbling paint, no holes, no "patches" by the previous owner. I'd imagine that you're more interested in converting a car to electric, and less interested in fighting cancer.

Just my 2c.
 

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Discussion Starter #5
Rusty floor pans can be telling. Where did the water come from? Is the windshield seal bad? Is the cowl rusted through and it's draining inside the car? Was it driven on salty roads in the winter, rusting from the bottom, and there's further damage? What do the inside of the doors look like (behind the door cards)? Wheel wells (inner and outer)? Trunk floor? Frame rails? Pinch welds on the body? It's normal to find nasty rust in many of those places that would render an otherwise fun project a bottomless money pit.
Good tips. I'll try to keep that all in mind.

Welding floor pans is not a big deal, necessarily, but anything else on the car can be.
Yeah, the extent of my experience on bodywork is replacing a rusted through wheel well, and that was only as hard as a sawzall and a junkyard. Even then it never really went back together the same way.

Check for bondo - bring a magnet. There may be gaping rust holes covered with bondo and then painted. A magnet will help you find that.
Dumb question, but... why would I care?

If they bondo'd over a hole, and I can't tell visually, what's the thing I should be worried about?

There are enough cool cars out there - if the rust is anything more than just on the surface (minimal pitting), I'd just walk away.
That's my conundrum. I have half-assedly kept an eye on anything cheap and interesting enough that I'd care to convert it. I'm not a fanboy of any particular car. Anything less crappy is going to be more expensive. I probably am not interested in spending enough money on a vehicle that isn't going to need work. Kind of a pick your poison situation.

The thing I've heard most about "cheap" conversions is "I wish I spent more on a vehicle that didn't need as much work". So, I dunno. Maybe I have lower standards than other people.

No bubbling paint, no holes, no "patches" by the previous owner. I'd imagine that you're more interested in converting a car to electric, and less interested in fighting cancer.
Indeed, but I'm also cheap and it's not an essential.

This one is certainly going to need to be completely repainted. It's already got whole patches where paint was sanded off, I can only presume 40 year old paint got thin and rusted. I'm okay with that. Holes through the exterior would probably scare me away. Holes on the interior or floorboards make me grouchy but not scared. The things I don't know enough to ask about scare me the most.

Good advice all around, you gave me some particular things to pay attention to.
 

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I think that running condition is good, because even though you don't care about the engine, driving it can tell you if it has sound suspension, braking, and steering components that you will want to use.

The Opel GT is a "mini Corvette" in styling (I actually like it better than the corresponding third-generation Corvette), but not in chassis - it has a beam axle rear suspension, similar to the Chevette and other Opel-derived GM models of the era. That's okay, I suppose, but affects what powertrain conversion options are viable.

Anything obscure from this era could be a challenge for parts availability. It is generally similar to the Chevrolet Chevette mechanically, but since the Chevette's T-platform is shared with the Opel Kadett C, and the Opel GT is mechanically based on the one-generation-earlier Kadett B, there might not be any useful interchangeability. Even Chevette parts are probably rare by now.

Since there are no rear seats anyway, it might be possible to mount a pair of battery packs flanking the propeller shaft (driveshaft) under the rear parcel deck, to avoid making an excessively front-heavy car and to fit in enough battery... although it would probably be a substantial bodywork project, and there's little length available due to the short wheelbase.
 

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Dumb question, but... why would I care?

If they bondo'd over a hole, and I can't tell visually, what's the thing I should be worried about?
A hole patched with something (fiberglass?) and covered with filler is a hole which is likely going to continue to rust. The filler will also likely crack and even fall out, so even if it looks good now, it won't likely stay that way. Filler is not structurally useful, so it's no so bad in a fender, but could be scary in more critical locations.
 

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This is going to be a painful car, a cheap Opel GT!, I did a 1969 once where we had to fit a TVR V8, admittedly we had to have panels repressed and replaced the entire floor and fixed all the chassis rust, the cost was astronomical, the customer didn't care because he wanted that particular car, theres a reason they are so light. I'd done my part but I know the body work was at 20,000 GBP and it hadn't even been painted. This was a car that passed its MOT and was supposed to be a good example. Sure you may get lucky, I'm still waiting to find an original RS200 in a barn for $1000, but unless you really really love this car I would inspect every inch, and be ready to walk. By the way, I love these baby corvettes, my heart would say go for it, but my head having already been there once says look twice, think 3 times, budget 4 times.
I'll see if I can find the pictures, it was 15 years ago now.
 

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As this conversion shows, a battery pack location is the behind the axle, where the fuel tank is originally. A bad location for mass dynamically, and bad in a rear-end collision, but you might need the space...
 

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Hi Matt
I would say that an Opel GT is a superb car to convert - looks excellent

The only issue would be battery space - it may be better to get it's big brother (a Corvette) simply so that you have room for enough batteries

On that front do analysis on YOUR driving

I found that most of the time I was driving less than 40 km - but on the days that I exceeded 40 km I needed 150 km

So my device was fine with its 40 km range - but I would have needed four times the batteries for the "next step"
 

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Good tips. I'll try to keep that all in mind.



Yeah, the extent of my experience on bodywork is replacing a rusted through wheel well, and that was only as hard as a sawzall and a junkyard. Even then it never really went back together the same way.



Dumb question, but... why would I care?

If they bondo'd over a hole, and I can't tell visually, what's the thing I should be worried about?



That's my conundrum. I have half-assedly kept an eye on anything cheap and interesting enough that I'd care to convert it. I'm not a fanboy of any particular car. Anything less crappy is going to be more expensive. I probably am not interested in spending enough money on a vehicle that isn't going to need work. Kind of a pick your poison situation.

The thing I've heard most about "cheap" conversions is "I wish I spent more on a vehicle that didn't need as much work". So, I dunno. Maybe I have lower standards than other people.



Indeed, but I'm also cheap and it's not an essential.

This one is certainly going to need to be completely repainted. It's already got whole patches where paint was sanded off, I can only presume 40 year old paint got thin and rusted. I'm okay with that. Holes through the exterior would probably scare me away. Holes on the interior or floorboards make me grouchy but not scared. The things I don't know enough to ask about scare me the most.

Good advice all around, you gave me some particular things to pay attention to.
None of my concerns are about cosmetics. Ultimately, Anything cosmetic can be filled, painted, buffed to a shine. Rust will kill your car, and rust that is covered will continue to rust, usually with moisture betting between the rust and the filler, until it all falls off and reveals a gaping hole. In a unibody car, especially with the possibility of more power and a lot more weight, this is a potentially dangerous situation.

I bought a rusty Mustang several years back. Never again. Trust me, don't be that guy unless you just love body work. Making your car look nice for 6 months at a time while it molders underneath body filler that keeps falling off is a painful way to do a project, and doing it right is even more expensive.

I don't know the condition of this Opel, and it really could be OK. If there is any significant rust, though, it is a terrible candidate from the get-go. Additionally, your description of sanded paint sounds a lot more like filled dents or holes. Picture is worth a thousand words, here.

That being said, I would love to drive an e-Opel. That'd be a keen little car.
 

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I like building things cheap, I'm not looking for performance, I want something to build without breaking the bank or feeling guilty about wrecking a classic, so, it seems a good fit that way.

...
Doesn't have a hatchback or a trunk, just a weirdly large parcel shelf.
Due to the lack of cargo access, I couldn't tolerate one of these as a daily driver, so it would have to be a performance car for me. Do the characteristics of this car really fit what you want it to do?

While the "don't wreck a classic" reasoning has some validity, I wouldn't worry about it. The world only needs a handful of each significant model preserved, at the most. I'll never be able to afford to buy anything that is worthy of preservation, so if I can buy it, I have no problem with taking it out of the inventory of preserved artifacts.
 

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Discussion Starter #14
Brian said:
even though you don't care about the engine, driving it can tell you if it has sound suspension, braking, and steering components that you will want to use.
Sadly, I'm not that experienced of a driver. Also I've only ever driven stick on a tractor and that's been 10 years, so, my brain is going to be filled with thoughts of just actually driving. I might be behind the wheel and think everything is fine and there be obvious crap going wrong.

I doubt it's insured, says it's sat for a year. Complicates things. At minimum I'll probably ask the owner to drive it and sit in the passenger seat.

That's okay, I suppose, but affects what powertrain conversion options are viable.
Howso?

What would I want to do differently back there?

The filler will also likely crack and even fall out, so even if it looks good now, it won't likely stay that way. Filler is not structurally useful, so it's no so bad in a fender, but could be scary in more critical locations.
Ahh, gotcha.

So, if someone bondo'd the rusted base of the B pillar or something, instead of using actual metal replacement, it's likely a hackjob where they never cleaned out the rust either and it's held on by the unanswered prayers of orphans.

There is at least one relatively well-known Opel GT conversion which was actually completed:
https://www.youtube.com/playlist?list=PL15AC1C151616A09B <-- I've been making my way through that today already.

Due to the lack of cargo access, I couldn't tolerate one of these as a daily driver, so it would have to be a performance car for me. Do the characteristics of this car really fit what you want it to do?
I would rather it be a hatchback, and I'm half-tempted to frame one out with square tube and the grind it into existence.

I have a van I need for work occasionally, so, I'll always have that available. Most of my daily stuff is just moving me around. A bicycle was fine for me for a decade of adult life, just a pain in the ass in winter.

I want something that's cheap to drive (electric), small, and moderately fun. I can't think of what vehicle I'd want instead. Something boring like a Mazda hatch or a Golf maybe, but, for the price/value of doing that, I might as well just buy an old Leaf.


="x.l.r.8"]look twice, think 3 times, budget 4 times.
I certainly wouldn't be spending 5 figures on panel work. Nor even 4 figures. It's going to look ugly and shitty like a hobo's coat if I'm patching the interior, not something sculpted to be beautiful. And I'm okay with that, somewhat.


Duncan said:
The only issue would be battery space - it may be better to get it's big brother (a Corvette) simply so that you have room for enough batteries
If I'm working on this, it needs to fit in a 15' garage. A real 'Vette won't. Also, real 'Vettes cost money, even in bad shape. Also, if I had a real 'Vette, I probably would keep the engine.

It's a delicate balance. I want something cheap and sort of crappy enough that I don't feel bad for converting it on a cheap budget. But I don't want something so bad that it costs me more money than spending extra to begin with.

The good news is that I'll probably be building a pack from 18650s, so I can squeeze battery space into smaller areas than most other form factors would allow.

I probably want something like 100km range. On something tiny like this, it might get 250wh/mile, so, I don't need all that much battery.


[quote="JBMan]Rust will kill your car, and rust that is covered will continue to rust, usually with moisture betting between the rust and the filler, until it all falls off and reveals a gaping hole.[/quote]

I had not even considered that someone would be foolish enough to bondo over a rusted area, without removing the rust first. Naturally if a chop shop is just shoving it out the door, I guess they might.

...

I guess I'll go look at it and try to take a million pictures in the next couple days.

Thanks everyone. I was approaching this with a little too much voting on hope rather than practicality. I'll see just how bad the structural rust is, if any.
 

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It's not just a hack job covering rust thing. Metal must be properly prepared and treated, even with filler. Filler is porous, so if it is not properly waterproofed (good paint or whatever, not just primer which is also porous), even a "clean" repair will eventually fail. Body filler on a hole is just cheap, and it's very common on older cars. It's a much bigger deal than you think. Anyway, hope it works out.

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... it has a beam axle rear suspension, similar to the Chevette and other Opel-derived GM models of the era. That's okay, I suppose, but affects what powertrain conversion options are viable.
Howso?

What would I want to do differently back there?
I can't say what you might want to do. ;)
The option which becomes much more difficult because of the beam axle (rather than independent rear suspension) is placing the motor at the back, such as with a salvaged EV drive unit.

If you keep any kind of beam axle (and if you're keeping that design, you might as well just keep the original axle), the motor needs to be at the end of a shaft. The Opel GT's shaft is in a tube which forms part of the suspension, so the motor output (or the output of any transmission which is used) must be essentially at the stock transmission output.
 

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Discussion Starter #17
If you keep any kind of beam axle (and if you're keeping that design, you might as well just keep the original axle), the motor needs to be at the end of a shaft. The Opel GT's shaft is in a tube which forms part of the suspension, so the motor output (or the output of any transmission which is used) must be essentially at the stock transmission output.
Ahh, I hadn't considered replacing it with a standard EV transaxle or somesuch. Did consider altering it to be FWD and doing that though, if there was a suitably-sized front everything I could manage to swap, but I suspect on a vehicle this little, there haven't been any EVs made that could donate. Then I'd be less scared of driving it in the winter. Just an idle thought though.

I'm somewhat contemplating if I need a transmission at all, or if I could direct drive it, putting the motor low and in the rear in what I imagine is under the parcel shelf somewhere. Maybe at only a slightly increased angle into the diff.

Motor is going to weigh more than the batteries I imagine.

The motor I have (not that my heart is set on it, but, I have it, and it was free) is, relatively, gigantic. I think it probably weighs 350lbs, which is 100lbs more than the original engine.



11" dia x 16" long.

AC induction motor. ~25HP 1 hour rating, 36 of 48v IIRC.
 

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Ahh, I hadn't considered replacing it with a standard EV transaxle or somesuch. Did consider altering it to be FWD and doing that though, if there was a suitably-sized front everything I could manage to swap, but I suspect on a vehicle this little, there haven't been any EVs made that could donate. Then I'd be less scared of driving it in the winter. Just an idle thought though.
Various drive units would fit in the front, but the Opel GT front suspension and hubs won't work with front wheel drive. If you take everything (drive unit and suspension) from a donor vehicle, the track width would probably be an issue. If you mix and match bits, the Mitsubishi i-MiEV or Smart ForTwo drive units might be the smallest.

Front wheel drive might not be better in winter. Front-heavy rear wheel drive vehicles are problematic, but as long as the weight distribution is relatively even, rear wheel drive is actually easier to control.

I'm somewhat contemplating if I need a transmission at all, or if I could direct drive it, putting the motor low and in the rear in what I imagine is under the parcel shelf somewhere. Maybe at only a slightly increased angle into the diff.
You could put the motor where the transmission is now, but you can't put it much further back because of that non-independent suspension. The axle moves up and down with suspension travel, but the motor doesn't, so there must be a jointed shaft between them of reasonable length. Even if you change the suspension to not need the tube which the shaft runs in, there still needs to be some shaft length.

This photo shows some of the axle and suspension components, including the propeller shaft (or driveshaft, item #2) and the torque tube (item #4) which surrounds it (when installed) and controls the axle.


In the photo below, see the joint right in the middle, midway between the transmission and the axle, at the driver's hip (with the little arrow pointing to it)? That's the bearing and joint which is fixed to the structure, with the shaft portion behind it running in the tube which controls the rear axle.
 

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If you can provide enough voltage for that motor to maintain power at high enough speed to allow use without a multi-speed transmission, and it can work that the speeds resulting from the rear axle reduction ratio, and can fit it in the transmission space, then you can put a battery pack in the front... but the car will be problematically front-heavy. More likely, you end up with it in place of the motor, like Rickman did; in that case, almost all of the battery must end up in the back.

I probably want something like 100km range. On something tiny like this, it might get 250wh/mile, so, I don't need all that much battery.
Motor is going to weigh more than the batteries I imagine.

The motor I have (not that my heart is set on it, but, I have it, and it was free) is, relatively, gigantic. I think it probably weighs 350lbs, which is 100lbs more than the original engine.
100 km at 155 Wh/km is 15.5 kWh... or an entire battery pack from a typical plug-in hybrid (such as a Chevrolet Volt or Chrysler Pacifica). That's substantially heavier than even that lump of motor.

If the cargo shelf is long enough (it goes all the way from the seats to the tail), and you can give up the cargo space, then perhaps a battery pack like Duncan's (two rows of Volt modules side-by-side) would fit (but with a housing, please, since it would be in the passenger compartment).
 

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Discussion Starter #20
Even if you change the suspension to not need the tube which the shaft runs in, there still needs to be some shaft length.
Ahh, I'd thought of everything else except this. Obviously the shaft needs to stretch and shrink during suspension travel, more-and-more-so the shorter the shaft is and the higher the magnitude of travel towards or away from the axle (90 degrees to vertical would be ideal, less so at a 20-30' pitch).

More likely, you end up with it in place of the motor, like Rickman did; in that case, almost all of the battery must end up in the back.
I'd rather motor in the back (where it never gets touched), and batteries in the front (which will need to be periodically inspected. Oh well.

100 km at 155 Wh/km is 15.5 kWh... or an entire battery pack from a typical plug-in hybrid (such as a Chevrolet Volt or Chrysler Pacifica). That's substantially heavier than even that lump of motor.
Not that I'm using Tesla packs, but Tesla packs are 209 Wh/kg = 74kg, or 165 lbs.

Motor is somewhere abouts 300.

My bare 18650 cells are at least near that ballpark for that amount, though I have to add all the framing, connections, wiring, racking, etc to them.
 
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